Add support early/late hooks in generate-zbm

Since generate-zbm only knows how to manage one ESP, it can be a
challenge to keep multiple redundant ESPs up-to-date on a system. To
help with this, Global.PreHooksDir and Global.PostHooksDir can now be
defined to point to a directory of executable hooks. These are executed
without any additional environment context or arguments.

bin/generate-zbm

@@ -194,6 +194,15 @@ if ( nonempty $config{Global}{BootMountPoint} ) {
   }
 }
 
+if ( nonempty $config{Global}{PreHooksDir} and -d $config{Global}{PreHooksDir} ) {
+  while (my $hook = <$config{Global}{PreHooksDir}/*> ){
+    next unless -x $hook;
+    Log("Processing hook: $hook");
+    my @output = execute(qq($hook));
+    Log( \@output );
+  }
+}
+
 # Create a temp directory
 # It is automatically purged on program exit
 my $dir     = File::Temp->newdir();
@@ -536,6 +545,15 @@ EOF
   safeCopy( $runConf{syslinux_temp}, $config{Components}{syslinux}{Config} ) or exit 1;
 }
 
+if ( nonempty $config{Global}{PostHooksDir} and -d $config{Global}{PostHooksDir} ) {
+  while (my $hook = <$config{Global}{PostHooksDir}/*> ){
+    next unless -x $hook;
+    Log("Processing hook: $hook");
+    my @output = execute(qq($hook));
+    Log( \@output );
+  }
+}
+
 END {
   cleanupMount;
 }
@@ -928,6 +946,11 @@ sub Log {
   chomp($entry);
   unless ( ref($entry) ) {
     print STDERR "## $entry\n";
+  } elsif ( ref $entry eq REFARRAY ) {
+    foreach my $line ( @{ $entry } ) {
+      chomp $line;
+      print STDERR "## $line\n";
+    }
   } else {
     print STDERR Dumper($entry);
   }

contrib/esp-sync.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+
+cleanup() {
+  if [ -n "${ESP_MNT}" ]; then
+    mountpoint -q "${ESP_MNT}" && umount -R "${ESP_MNT}"
+    [ -d "${ESP_MNT}" ] && rmdir "${ESP_MNT}"
+  fi
+}
+
+ESPS=(
+  "/dev/sdb1"
+  "/dev/sdc1"
+  "/dev/sdd1"
+)
+
+BMP="$( yq-go eval ".Global.BootMountPoint" /etc/zfsbootmenu/config.yaml )"
+if [ -z "${BMP}" ]; then
+  echo "Unable to determine BootMountPoint"
+  exit 1
+fi
+
+IMG_DIR="$( yq-go eval ".EFI.ImageDir" /etc/zfsbootmenu/config.yaml )"
+if [ -z "${IMG_DIR}" ]; then
+  echo "Unable to determine ImageDir"
+  exit 1
+fi
+
+IMG_REL="${IMG_DIR#"${BMP}"}"
+
+mount "${BMP}"
+
+if ! ESP_MNT="$( mktemp -d )"; then
+  echo "Unable to create temporary mountpoint"
+  exit
+fi
+
+trap cleanup EXIT INT TERM
+
+for ESP in "${ESPS[@]}"; do
+  if ! mount "${ESP}" "${ESP_MNT}" ; then
+    echo "Unable to mount ${ESP} at ${ESP_MNT}"
+    continue
+  fi
+
+  mkdir -p "${ESP_MNT}${IMG_REL}"
+  rsync --delete-after -avpP --include=zfsbootmenu\* --exclude=\* "${IMG_DIR}/" "${ESP_MNT}${IMG_REL}/"
+
+  if ! umount "${ESP_MNT}" ; then
+    echo "Unable to unmount ${ESP_MNT}"
+    exit 1
+  fi
+done

etc/zfsbootmenu/config.yaml

@@ -2,6 +2,8 @@ Global:
   ManageImages: false
   BootMountPoint: /boot/efi
   DracutConfDir: /etc/zfsbootmenu/dracut.conf.d
+  PreHooksDir: /etc/zfsbootmenu/generate-zbm.pre.d
+  PostHooksDir: /etc/zfsbootmenu/generate-zbm.post.d
 Components:
   ImageDir: /boot/efi/EFI/void
   Versions: 3

pod/generate-zbm.5.pod

@@ -38,6 +38,14 @@ A specific ZFSBootMenu version string to use in producing images. In the string,
 
 An array of additional arguments that will be passed to B<dracut> when generating an initramfs.
 
+=item B<PreHooksDir>
+
+The path of the directory containing executables that should be executed after I<BootMountPoint> has been mounted. Files in this directory should be B<+x>, and are executed in the order returned by a shell glob. The exit code of each hook is ignored.
+
+=item B<PostHooksDir>
+
+The path of the directory containing executables that should be executed after all images have been created and any file pruning has taken place. Files in this directory should be B<+x>, and are executed in the order returned by a shell glob. The exit code of each hook is ignored.
+
 =back
 
 =head2 Kernel

testing/setup.sh

@@ -171,6 +171,8 @@ if ((YAML)) ; then
   yq-go eval ".EFI.Stub = \"${STUBS}/linuxx64.efi.stub\"" -i "${yamlconf}"
   yq-go eval ".Global.ManageImages = true" -i "${yamlconf}"
   yq-go eval ".Global.DracutConfDir = \"${TESTDIR}/dracut.conf.d\"" -i "${yamlconf}"
+  yq-go eval ".Global.PreHooksDir = \"${TESTDIR}/generate-zbm.pre.d\"" -i "${yamlconf}"
+  yq-go eval ".Global.PostHooksDir = \"${TESTDIR}/generate-zbm.post.d\"" -i "${yamlconf}"
   yq-go eval ".Global.DracutFlags = [ \"--local\" ]" -i "${yamlconf}"
   yq-go eval "del(.Global.BootMountPoint)" -i "${yamlconf}"
   yq-go eval -P -C "${yamlconf}"